Flor-Essence(R) Herbal Tonic is a widely used and self-administrated complementary and alternative medicine often consumed by breast cancer patients to supplement conventional therapy. The eight herbs used in Flor-Essence(R) have importance in the Asian diet and medicines and have estrogenic, cytotoxic, anti-estrogenic, antimutagenic, and anti-oxidant characteristics which are associated with altering cancer risk in animals and humans. PhlP is a ubiquitous dietary mutagen. It is carcinogenic in rats and has been linked to increased cancer risk in humans. Our preliminary data indicate Flor-Essence(R) can inhibit the mutagenicity and cytotoxicity of PhIP. It is critical that commercially available dietary supplements be studied in model systems relevant to current human consumption and exposure. The hypothesis of this proposal is that Flor-Essence(R) has properties that interfere with PhlP-induced mammary cancer risk in humans. The Comet assay and the Sprague Dawley rat model will be used to test this hypothesis. Aim 1: To determine if Flor-Essence(R) alters the induction or repair of PhlP-induced DNA adducts in human cancer cell lines. Single strand DNA breaks formed after PhlP exposure can be quantified using the alkaline comet assay. Breast derived cell lines that differ in metabolizing enzyme activity and tumorigenic potential will be used to quantify PhlP-induced damage. Flor-Essence(R) will be administered to the cells before, during, or after PhlP exposure in order to determine if the timing of herbal tonic exposure affects the induction and repair of PhlP induced damage. Aim 2: To determine if PhlP induced mammary tumor development in the Sprague Dawley rat model is altered by exposure to Flor-Essence(R) Herbal tonic. PhlP will be used to induce mammary tumors in 7 week old rats consuming (a) water or 3% Flor-Essence(R) (b) throughout the study, (c) prior to and during carcinogen exposure, (d) after PhlP. Mammary tumor incidence, multiplicity, latency, and tumor pathologies will be compared. These experiments are designed to determine (a) if Flor-Essence(R) can inhibit the mutagenicity of PhlP in mammalian cells and (b) if Flor-Essence(R) exposure influences PhlP-induced mammary tumor development in rats. It is important to determine how currently used CAMs are interacting with dietary carcinogens to influence health. Science based information is needed so that people can make informed lifestyle choices.